Recently, a micro base station apparatus referred to as a femto cell (home base station: Home eNB, hereinafter, referred to as HeNB), which forms a small cell having a smaller communication area than that of a conventional cell has been developed for compensation of a dead zone in mobile phone networks.
Conventional large base station apparatuses to form cells having a large communication area (Macro base station: Macro eNB, hereinafter, referred to as an MeNB) determine the frame timing based on highly accurate time information acquired by, for example, GPS (Global Positioning System). Thus, highly accurate frame timing synchronization can be established between MeNBs. In contrast to this, considering costs and that HeNBs are mainly placed in buildings, it is difficult to provide HeNBs with GPS etc., and therefore the frame timings between an HeNB and MeNBs located around the HeNB are not synchronized with accuracy.
In view of the amount of calculations, it is desirable that the frame timings between an HeNB and an MeNB be synchronized with high accuracy so that the HeNB suppresses (cancels) interference from the MeNB. However, as described above, a large amount of calculations are required for suppressing interference from an MeNB when an HeNB cannot synchronize frame timing between the HeNB and an MeNB, and therefore apparatus costs rise, sharply.
Meanwhile, as a conventional technique for synchronizing the frame timings between the HeNB and the MeNB, the following technique is cited as an example. Specifically, Non-Patent Literature 1 proposes a technique in which an HeNB searches for a PBCH (Physical Broadcast Channel) and a SCH (Synchronization Channel) from an MeNB and thereby determines the frame timing of the HeNB. In the above conventional technique, the HeNB synchronizes the frame timing between the HeNB and the MeNB by searching for a PBCH and a SCH from the MeNB and determining the frame timing of the HeNB.